The monograph is devoted to physical and electrodynamic methods of studying multilayer structures. The method of impedance solved the problem of propagation of one-dimensional and electromagnetic waves during normal and inclined (longitudinal and transversal polarization) fall on a structure consisting of an arbitrary number of environments with different parameters. Cases of unidirectional and counter waves are considered. Introduced the concept of generalized impedance for wave processes. Some impedance methods are considered, which solve various problems about wave propagation. An algorithm for recalculating impedance from the subsequent boundary to the previous one when direct and oncoming waves fall. With the help of this algorithm, the impedances of the media and amplitudes of the outgoing direct and oncoming waves are obtained when falling on a multilayer structure consisting of two to five and an arbitrary number of media.. The work will be useful to students and graduate students of physical specialties of universities and institutes, as well as teachers, engineers and researchers in the field of technical sciences .